Automatic file-sharpening machine



Jan. 10, 1956 R. L. DAY 2,729,921

AUTOMATIC FILE-SHARPENING MACHINE Filed May 17, 1954 3 Sheets-Sheet 1 4GINVENTOR, eosser 4. 004 x fir 0.6?

Jan. 10, 1956 R. L. DAY 2,729,921

AUTOMATIC FILE-SHARPENING MACHINE Filed May 17, 1954 3 Sheets-Sheet 2 INVEN TOR, 805597 L. 09V

BY fi a aria/Quays Jan. 10, 1956 R. DAY 2,729,921

AUTOMATIC FILE-SHARPENING MACHINE Filed May 17, 1954 3 Sheets-Sheet 3 IsI INVENTOR BOBEQT 4. 05W

I? arraeusys' United States Patent AUTOMATIC FILE-SHARPENWG MACHINERobert L. Day, Sun Valley, Califl, assignor of one-half to Harry L.Williams, Los Angeles, Calif.

Application May 17, 1954, Serial No. 430,305

9 Claims. (Cl. 51--96) This invention relates to improved automaticfilesharpening machinery. A feature of this invention is the provisionof machinery for sharpening files having arcuate teeth.

Another feature of this invention is the provision of novel machineryfor automatically sharpening files having curved teeth.

Still another feature of the invention is the provision of a new anduseful machine for automatically sharpening a file having curved teeth.

These and other features of the invention are provided by a machinewherein a file to be sharpened is held on a file-holding platform. Thisplatform is given an oscillatory motion about a pivotal point. Agrinding wheel is positioned at a distance from the pivotal pointsubstantially equal to the radius of the curved teeth of the file to 9be sharpened. Means are provided for lowering the grinding wheel ontoone of the teeth of the file and for subsequently continuously loweringthe grinding wheel to compensate for wear. Means are also provided foradvancing the file to present a succeeding tooth to be sharpened to thegrinding wheel each time the oscillating plat form attains one of itsextremes of oscillation.

The novel features that are considered characteristic of this inventionare set forth with particularity in the embodiment of the presentinvention;

Figure 2 shows the manner in which a file is passed under the grindingwheel by the oscillating motion of the file-holding platform;

Figure 3 shows the relative operative grinding wheel and a file;

Figure 4 is a section taken on line 4-4 of Figure 1, showing the detailsof the file-holding platform;

Figure 5 is a section through the file-holding platform taken on line5-5 of Figure 1;

Figure 6 shows in perspective the details of the file holder employed inthe embodiment of the invention;

Figure 7 is a section through the mounting of the file holder taken onthe line '7-7 of Figure 5;

Figure 8 shows in perspective details of a file support which supportsthe part of the file under the grinding wheel;

Figure 9 shows details of the mechanism as seen in Figpositions of aures 1 and 4 for lowering the grinding wheel upon the file continually;

Figure 10 shows a file having file teeth whose axis of concentricity isnot on the longitudinal axis extending through the file;

Figure 11 shows how a file may beshifted to a position for sharpeningwhich compensates for such lack in concentricity;

Figure 12 shows a cross-section through the file-holding platform, thelocation of which section is on line 12-12 in Figure 14;

Figure 13 is a sectional view of the file holder and the surroundingstructure taken on the line 13--13 of Figure 12;

Figure 14 is another sectional view through the fileholding platformtaken on the line 14--14 of Figure 12;

Figure 15 is another section to show the mechanism for supporting andholding a file, which section is taken on the line 1515 of Figure 12;

Figure 16 shows the advancing bar used for successively advancing thefile teeth under the grinding wheel;

Figure 17 shows a guide bar which helps to guide a file under thegrinding wheel; and

Figure 18 shows the guide bar plate through the groove of which the fileis guided to be pushed. under the grindin g wheel.

Figure 1 is a drawing of an embodiment of my invention consisting of asupporting post 10 upon which there is adjustably clamped a baseplatform 12. As may be better seen in Figure 4, a file-holding platform14 is supported on this base pivotally. A motor 16 is also supportedfrom this base. This motor has a belt 18 which drives a wheel 20 which,in turn, drives a crank arm 22 which is connected by a link 23 to oneside of the pivotally supported file-holding platform. Accordingly, whenthe motor is driven, the file-holding platform 14 will oscillate aboutits pivotal support 24. A grinding wheel 26 and an associated drivingmotor 23 are supported on opposite ends of a yoke 30 which is pivotallysuspended from the post or column 10. The yoke size is such that thegrinding wheel 26 is supported over the file-holding platform 14 when itis in its central position. The weight of the electric motor 23 tends topivot the yoke so that the grinding wheel 26 is urged upwards. However,a flat member 32 is slidingly mounted on the column. It has a locknut 34attached to one side and an adjustable screw 36 attached to the other.The adjustable screw 36 is used to bear down on the side of the yoke 30on which the grinding wheel 26 is attached. The sliding fiat member 32is supported by means of a screw member 38 which extends threadablythrough the locknut 34 and through a threaded collar 40 which isrotatably supported from the base platform 12. This can be seen betterfrom Figures 4 and 9. The collar has a ratchet ring 42 around it. Itwill be appreciated that as the screw member 38 is pushed upward ordownward by turning the collar 40 the adjustable screw 36 bears down orlets up on the side of the yoke on which the grinding wheel is mounted.Thus the grinding wheel position may be ad justed to be in position uponthe tooth 46 of a file 44 mounted on the file-holding platform, as maybe more readily seen from Figure 3.

The file-holding platform 14 is oscillated by driving the motor 16supported from the base platform, the motor 28 supported from the yokeis driven, and, through the associated drive belt, drives the grindingwheel. The oscillating file-holding platform passes a file toothe underthe grinding wheel by describing an arc in the manner illustrated inFigure 2. The grinding wheel is positioned at a distance from thepivotal mounting: of the file-holding platform substantially equal tothe radius of curvature of a file tooth.

Means are provided for gradually lowering the grinding wheel in order tocompensate for the reduction in diameter occasioned by the wear. Thismay be seen by regarding Figures 1, 4, and 9. As previously stated, thecollar 40 which is rotatably mounted upon the base platform 12 has aratchet ring 42 mounted around its outside. A pawl member 48 is springbiased to be in tender with the ratchet ring. A pawl driving rod 50 ismovably supported and is attached at one end to the pawl member. Aspring 52 is employed to bias the rod. The other end of the rod ispushed by the oscillating file-holding platform when it reaches oneextreme of oscillation. The spring then returns the rod to its initialposition. It will be appreciated, therefore-, that when the file-holdingplatform pushes the rod it also actuates the pawl and ratchet to rotatethe collar a given amount. This causes the screw member 38 to movedownward. The flat member is also moved downward, causing the grindingwheel to be moved downward a desired amount.

A file holder mechanism is provided for holding the file upon thefile-supporting platform under the grinding wheel. Figure 4 shows thisfile holder in plan and Figure 6 in perspective. It consists of twoparallel members 60, 62 and two parallel crossbar members 64, 66

which serve to pivotally support the two parallel mem bers in parallel.The inner surfaces of the two parallel members are brought to a somewhatnarrow 'or knife edge 68 in order to support and hold the file inserted:therebetween' againstsidewise motion and yet permit motionlongitudinally with a minimum of friction. The two grossbar members aresupported by two posts 70, 72. ,The posts are pivotally supported in twofiat bearing members 71, 73 which, in turn, are supported on a fileholder base ;member 75. Figure 7 shows the'det'ail of the support by thebearing member. From one of the posts 70, a spring 'biasyis applied by aspring 74 to one of the crossbar members 64 in order to bring the twoparallel members 60, 62 together. In order to spread the paral lelmembers, a key (not shown) may be inserted through the square openingprovided in a rotating member 76 which is turned in a direction againstthe spring bias to engage. a projection 78 on the under side of one ofthe parallel members 62 to thus open or spread the two parallel members.This may be more readily seen in Figure 5.

Underneath the portion of a file under the grinding wheel which isclamped by the file holder there is provided aspring-biased filesupport. This serves to support the file against the downward thrust ofthe grinding wheel. Figure 8 is a perspective view of this platform.

Sectional views may be seen in Figures 12 and 14. Referring now toFigure 8, the file support includes a lower flat member 80 and an upperfiat member 82. The upper flat member bears against the lower surface ofthe file held in the file holder. It is rotatably supported along itslongitudinal axis above the central portion of the lowermember by twohinge members 84, 86 which are attached to the lower fiat member. Fourstops 88 are provided (only two of which may be seen) on the under sideof the upper flat member which limit the 1 amount of rotation to adesired amount. The lower flat member is alsorotatably supported on oneside by two hinge members 90, 92. These are fastened to a wall of thefile-holding platform, as may be seen in Figure 15. The other side ofthe lower fiat member is supported by a spring 94 (shown in Figures 14and 15). This spring pushes upward against the lower fiat member from aplate 96 which rests on the file-holding platform 14. The height of thespring-biased side of the lower flat member, and thereby the force withwhich the file is urged against the grinding wheel, is adjusted by anadjustable screw 08 which has a lever arm 100 at one end andis threadedthrough the lower platform extending through the spring 24 into the fiatmember 96. The end extending into the ast inefnher is held there,permitting the screw 98 to [he uraa but not withdrawn. Thus by turningthe lever arm the one end of the lower flat member can be lowie d orraised. This changes the spring bias and the upwaidforc'e of the uppermember against a tile. It will be appreciated that this arrangementpermits the springbiased file support to be self leveling and tocompensate for variations in height or wear of file teeth being ground.

Figure 10 shows a portion of a file wherein the axis of concentricity102 of the file teeth does not fall on the longitudinal axis 104 of thefile. Since the file-holding platform is oscillated in an are which hasthe same center as the file teeth, it will be appreciated that whenthere is lack of concentricity the grinding wheel will not sharpen allof a file tooth. However, if a file, having such lack of concentricity,is shifted or turned in a manner shown in Figure 11, the file tooth 106will be completely sharpened since its arc is made to coincide with theare through which the platformtravels under the grinding wheel. Thisrequires that the file be permitted to rotate slightly as it passesunder the grinding wheel. This is achieved by mounting the file holderbase member 75 on a bearing 106 (see Figure 12). The bearing ispositioned right under the grinding wheel. This permits the file to berotated to compensate for the lackofconcentricity. The degree of suchrotation is limited by the supporting wall structure 107, 108 on thefile-holding platform. I

In order to achieve automatic operation, the teeth of a file must besuccessively advanced under the grinding wheel. A plate 110 having agroove 112 (shown in Figure 18) is mounted over a file to be sharpened,as may be seen from Figure 18. Two guide blocks 114, such as are shownin Figure 17, are used with the plate 110; one is mounted on either sideof the groove in the positions indicated by the holes. The actualadvancement of the file teeth is performed by the teeth-advancing blockshown in Figure '16, having a teeth-engaging member 116 and aroller-engaging member 118. The end of the teeth-engaging member isshaped to conform to the curve of the file teeth and is pointed so thatit can readily slip behind the ridge of a tooth, as can be seen inFigure 12. The teethengaging member and roller-engaging member have apivotal joint 120 at their lower ends and have a spring 122 biasing themapart at their upper ends. Thus, since as shown in Figure 12 theteeth-advancing block has its roller-engaging member sliding in thegroove 112 over the file, the teeth-engaging member is urged pivotallydownward by the spring 122 to engage a tooth for advancement. Theroller-engaging member has an arcuate back portion 124 which crosses itto form a T. A projecting member 126 is mounted on the arcuate portion.It has a hole therein to receive a stop screw 128. The stop screw isadjusted to limit the amount of backward travel given to theteeth-advancing block by two'springs 130 which are positioned betweenthe guide blocks 114 and the T extensions of the arcuate back portion124 (see Figures 5 and 12). V

Referring now to Figures 1 and 4, the reason for the back structure ofthe teeth-advancing block will be seen. Two roller members are mountedon the base platform 12 at a height equal to that of the arcuate backportion.

Each time the file-holdingplatform approaches an extreme of itsoscillation, the teeth-advancing block is urged inwardly by a roller. Inbeing urged inwardly, it moves forward and carries therewith the file.The distance it moves may be adjusted by adjusting the position of theroller. As shown in Figure 4, means are provided consisting of anadjusting screw 136 and a threaded ring 138 for properly positioning theroller to enable the movement of the file only one tooth distance. Thespring 140 holds the roller arm tight against the adjusting screw. Thearcuate back portion is shaped to engage the rollers.

Accordingly, in operation, the file is mounted by opening the fileholder and depositing the file therein with the first tooth under thegrinding wheel and then locking the file holder. Adjustments are made sothat on each extreme of oscillation the file advances only one tooth.This can be done'by adjusting the positions of the two roller wheels132, 134 with the adjusting screws 136 and the stop screw 128 in thetooth-advancing mechanism. The grinding wheel is then lowered and theautomatic filesharpening mechanism is then started. The platformoscillates and the file is progressively advanced past the grindingwheel until every tooth has been sharpened. The file is then removed,turned over and replaced, and the file teeth are then automaticallysharpened on that side.

The grinding wheel and its associated driving mechanism and a file canbecome hot during a grinding operation. Any of the well knownarrangements for air cooling or spraying of a liquid coolant may beemployed in order to keep the apparatus cool.

Accordingly, there has been described and shown herein a novel anduseful mechanism for automatically sharpening file teeth.

I claim:

1. Apparatus for sharpening files having curved teeth comprising asupporting column, a base platform supported from said column, afile-supporting platform pivotally mounted on said base platform, meansto hold a file on said platform, means to adjustably support a grindingwheel from said column over said means to hold a file with its grindingedge at a distance from said pivotal mounting of said file-supportingplatform substantially equal to the radius of curvature of a file tooth,means to oscillate said file-supporting platform. about its pivotalmounting to pass a file tooth under said grinding wheel, means actuatedwhen said file-supporting platform is at one extreme of its travel tolower said grinding wheel a sufiicient distance to compensate forreduction in diameter caused by wear, and means actuated at each extremeof oscillation of said file-supporting platform to advance a succeedingfile tooth under said grinding wheel.

2. Apparatus as recited in claim 1 wherein said means to hold a file onsaid platform includes a spring-biased means to hold a file by theedges, a spring-biased means to urge said file upwards toward saidgrinding Wheel, means to pivotally support said spring-biased means tourge said means to hold a file by the edges upwards at a pointunderneath said grinding wheel, and means to limit the amount of saidso-supported means is permitted to pivot.

3. Apparatus as recited in claim 2 wherein said springbiased means tohold a file by the edges includes a first pair of parallel bars, betweenwhich a file is placed, a pair of parallel crossbars, means to pivotallysupport each of said first pair of parallel bars on each of said pair ofparallel crossbars to always maintain said first pair of bars paralleland said pair of crossbars parallel, means to apply a spring bias to oneof said crossbars to urge said first pair of parallel bars together.

4. Apparatus as recited in claim 1 wherein said means to adjustablysupport a grinding wheel from said column includes a yoke pivotallyattached to said column, means to support said grinding wheel from oneend of said yoke, and means attached to the other end of said yoke topivot said grinding wheel away from said file-supporting platform, andsaid means actuated when said file-supporting platform is at one extremeof its travel to lower said grinding wheel a sulficient distance tocompensate for reduction due to wear includes a flat member slidablyattached to said column above said yoke, a locknut attached to one sideof said flat member, an adjustable screw threaded through the other sideof said flat member to adjustably contact said pivotally attached yokeon the grinding wheel side of its pivotal attachment, a collar havingits interior threaded and ratchet teeth mounted on its exterior, meansto rotatably support said collar on said base platform with said collaropening aligned with said locknut opening, an opening in said baseplatform underneath said collar opening, a screw threaded through saidlocknut and said collar and extending through said opening whereby saidflat member is adjustably supported above said yoke, a pawl, meanssupporting said pawl at a position to be moved when said file-supportingplatform reaches one extremity of its oscillation to engage 'and'rotatesaid collar by its ratchet teeth whereby said screw, said flat memberand its adjustable screw are lowered to lower said grinding wheel anamount to compensate for its reduction in diameter due to wear.

5. Apparatus as recited in claim 1 wherein said means to advance asucceeding file tooth under said grinding wheel includes aroller-engaging member slidably supported over the position of a file onsaid file-supporting platform, means to yieldably bias said member to agiven position over said file position, a first and a second roller,means supporting said first and second rollers at positions on said baseplatform on either side of said file-supporting platform to engage andmove said block from said given position when said file-supportingplatform approaches either extreme of oscillation, a tooth-engagingmember having one end adapted to engage a file tooth, means pivotallysupporting the other end of said toothengaging member at the lower endof said slidably supported roller-engaging member and means to yieldablybias said one end of said tooth-engaging member downwards towards afile.

6. Apparatus for sharpening files having curved teeth comprising asupporting column, a base platform supported from said column, afile-supportingplatform pivotally mounted on said base platform, meansto oscillate said file-supporting platform about its pivot, a fileholder including a first pair of parallel bars between which a file isplaced, a pair of parallel crossbars, means to pivotally support each ofsaid first pair of parallel bars on each of said pair of parallelcrossbars to always maintain said first pair of bars parallel and saidpair of crossbars parallel, and means to apply a spring bias to one ofsaid crossbars to urge said first pair of parallel bars together, meansto mount said file holder on said file-hold ing platform, means topivotally support said file holder on said file-holding platform, meansto limit the amount said file holder is permitted to pivot, and means toadjustably support a grinding Wheel from said column over said fileholder at a distance from said file-holding platform pivotal mountingsubstantially equal to the radius of curvature of a file tooth.

7. Apparatus for sharpening files having curved teeth comprising asupporting column, a base platform supported from said column, afile-holding platform pivotally mounted on said base platform, means tooscillate said file-holding platform about its pivot, a file holderincluding a first pair of parallel bars between which a file is place, apair of parallel crossbars, means to pivotally support each of saidfirst pair of parallel bars on each of said pair of parallel crossbarsto always maintain said first pair of bars parallel and said pair ofcrossbars parallel, and means to apply a spring bias to one of saidcrossbars to urge said first pair of parallel bars together, means toyieldably bias upwards a file held in said file holder, means topivotally support said file holder on said file-holding platform, meansto limit the amount said file-holding frame is permitted to pivot, ayoke pivotally attached to said column, a grinding wheel, means tosupport said grinding wheel from one end of said yoke over a file onsaid file-holding platform, means attached to the other end of said yoketo pivot said grinding wheel away from said file-supporting platform,means actuated when said file-supporting platform is at one extreme ofits travel to lower said grinding wheel a sufficient distance tocompensate for reduction due to wear including a fiat member slidablyattached to said column above said yoke, a locknut attached to one sideof said flat member, an adjustable screw threaded through the other sideof said fiat member to adjustably contact said pivotally attached yokeon the grinding wheel side of its pivotal attachment, a collar havingits interior threaded and ratchet teeth mounted on its exterior, meansto rotatably support said collar on said base platform with said collaropening aligned with said locknut opening, an opening in said baseplatform underneath said collar opening, a screw threaded through saidlocknut and said collar and extending through said opening whereby saidflat memher is adjustably supported above said yoke, a pawl,- meanssupporting said pawl at a position to be moved when said file-supportingplatform reaches one extremity of its oscillation to engage and rotatesaid collar by its ratchet teeth whereby said screw, said flat memberand its adjustable screw are lowered to lower said grinding wheel anamount to compensate for its reduction in diameter due to Wear.

'8. Apparatus for sharpening files having curved teeth comprising asupporting column, a base platform supported from said column, afile-supporting platform pivotally mounted on said base platform, meansto oscillate said file-supporting platform about its pivot, 21 fileholder including a first pair of parallel bars between which a file isplaced, a pair of parallel crossbars, means to pivotally support each ofsaid first pair of parallel bars on each of said pair of parallelcrossbars to always maintain said first pair of bars parallel and saidpair of crossbars parallel, means to apply a spring bias to one of saidcrossbars to urge said first pair of parallel bars together, means toyieldably bias a file in said frame upwards, means to pivotally supportsaid file holder on said file-supporting platform, means to limit theamount said file holder is permitted to pivot, means actuated at eachextreme of oscillation of said file-supportingv platform to advance asucceeding file tooth under said grinding wheel including a roller-enaging member slidably supported over the position of a file on saidfile-supporting platform, means means supporting said first and secondrollers at positions on said base platform on either side of saidfilesupporting platform to engage and move said rollererigaging memberfrom said given position when said filesupporting platform approacheseither extreme of osc'il lation, a tooth-engaging member having one endadapted to engage a file tooth, means pivotally supporting the other endof said tooth-engaging member at the lower end of said roller-engagingmember and means to yieldably bias said one end of said tooth-engagingmember downwards towards a file.

9. An automatic file-sharpening machine for files with curved teethincluding a file-supporting platform, means to hold a file on saidplatform,- means to position a grinding wheel with its grinding edge incontact with the teeth of a file clamped on said platform said meansincluding means to automatically lower said grinding wheel to compensatefor reduction in diameter occasioned by wear, means to move saidplatform and said wheel in a relative oscillatory motion to passsubstantially an entire file tooth under said grinding wheel, and meansto move, said file to bring a succeeding file tooth under said wheel forsharpening after said Wheel has passed over a file tooth.

References Cited in the file of this patent UNITED STATES PATENTS1,131,999 Denley et al. Mar. 16, 1915 1,777,135 Bailey Sept. 30, 1 9302,212,999 Faulder Q. Aug. 27, 1940 2,222,034 Jackson Nov. 19, 194()2,375,703 Swartzwelder May 8, 1945 FOREIGN PATENTS 35,361 SwitzerlandJan. 5, 1906 131,637 Switzerland Feb. 28, 1929

